DTC P16B8-71: Multi Flow Control Valve Actuator Stuck [10/2022 - ]: Procedure

1. Read the DTCs.

   Powertrain > Engine > Trouble Codes 

   Result

   Result	Proceed to
   P16B8-71 and other DTCs are output	A
   P16B8-71 is output	B

   HINT: 

   If any DTCs other than P16B8-71 are output, troubleshoot those DTCs first.

Result: 

A 

GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [10/2022 - 08/2023]  , or Refer to  DIAGNOSTIC TROUBLE CODE CHART [08/2023 - 10/2024]  , or Refer to  DIAGNOSTIC TROUBLE CODE CHART [10/2024 - ] 

Result: 

B 

See step  2

Refer to INSPECTION [10/2022 - ]

Result

Result: 

NG 

REPLACE WATER CONTROL VALVE. Refer to  REMOVAL [10/2022 - ] 

Result: 

OK 

See step  3

Pre-procedure1

• Disconnect the water control valve connector.
• Disconnect the ECM connector.

• Measure the resistance according to the value(s) in the table below.

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  B41-5 (FCM+) - B27-3 (FCM+)	Always	Below 1 Ω	Ω
  B41-4 (FCM-) - B27-4 (FCM-)	Always	Below 1 Ω	Ω
  B41-5 (FCM+) or B27-3 (FCM+) - Body ground and other terminals	Always	10 kΩ or higher	kΩ
  B41-4 (FCM-) or B27-4 (FCM-) - Body ground and other terminals	Always	10 kΩ or higher	kΩ

  Result

  Proceed to
  OK
  NG

Post-procedure1

• None.

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

Pre-procedure1

• Disconnect the water control valve connector.
• Inspect the ECM using an oscilloscope.
• Turn the ignition switch to ON.

• While the ignition switch to ON, check the waveform the terminals of the water control valve connector.

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *a

  Front view of wire harness connector (to Water Control Valve)

  *b

  Waveform of FCM+ terminal and FCM- terminal during fail-safe

  ECM Terminal Name	B41-5 (FCM+) - B41-4 (FCM-)
  Tester Range	2 V/DIV., 1 ms./DIV.
  Condition	Ignition switch ON

• While the ignition switch to ON, check the waveform between the FCM+ terminal and FCM- terminal during fail-safe.

  Standard

  25% duty waveform is output

  HINT: 

  • Check the operation circuit of the ECM by checking the waveform during fail-safe.
  • Because fail-safe is prohibited when the ambient temperature is 0°C (32°F) or less, work in a location where the ambient temperature is 5°C (41°F) or higher.
  • DTCs may be stored during this inspection. Check for DTCs and clear them using the GTS.

  Result

  Proceed to
  OK
  NG

Post-procedure1

• None.

Result: 

NG 

REPLACE ECM. Refer to  REMOVAL [10/2022 - ] 

Result: 

OK 

See step  5

1. Perform a customer problem analysis to check whether overheating occurred.

   HINT: 

   Check whether "High coolant temperature warning light" was displayed on the combination meter.

   Result

   Result	Proceed to
   Overheating occurred	A
   Overheating did not occur	B

Result: 

B 

See step  10

Result: 

A 

See step  6

1. Check the engine coolant quantity.

   Refer to ON-VEHICLE INSPECTION [10/2022 - ]

   Result

   Result	Proceed to
   At or below reserve tank LOW level or trace of coolant boiling over	A
   At or above reservoir tank LOW level and no trace of coolant boiling over	B

Result: 

B 

See step  10

Result: 

A 

See step  7

1. Check the engine cooling system for coolant leaks.

   Refer to ON-VEHICLE INSPECTION [10/2022 - ]

   OK

   No leaks.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

See step  9

Result: 

NG 

See step  8

1. Repair any engine coolant leaks.

   HINT: 

   Check for damage to parts due to overheating and replace any abnormal parts.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  9

1. Fill the reservoir tank up to the FULL line with engine coolant.

   HINT: 

   • Refer to REPLACEMENT [10/2022 - ]
   • Add engine coolant and perform air bleeding after repair.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  10

Pre-procedure1

• None.

• Clear the DTCs.

  Powertrain > Engine > Clear DTCs 

  Result

  Proceed to
  NEXT

Post-procedure1

• Turn the ignition switch off and wait for at least 30 seconds.

Result: 

NEXT 

See step  11

1. Read the Data List when the water control valve is operated.

   Powertrain > Engine > Active Test 

   Active Test Display
   Control the Multi Flow Control Valve Position

   Data List Display
   Actual Multi Flow Control Valve Position

   OK

   The value of the Data List item "Actual Multi Flow Control Valve Position" follows the command value and changes smoothly when the Active Test is operated in all ranges.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  14

Result: 

OK 

See step  12

Pre-procedure1

• None.

• Clear the DTCs.

  Powertrain > Engine > Clear DTCs 

  Result

  Proceed to
  NEXT

Post-procedure1

• Turn the ignition switch off and wait for at least 30 seconds.

Result: 

NEXT 

See step  13

Pre-procedure1

• Start the engine.
• Idle the engine for 120 seconds or more.
• Turn the ignition switch off and wait for at least 30 seconds.
• Start the engine from a cold condition.
• Drive the vehicle on urban roads until the Data List item "Coolant Temperature Controlling Value" rises to 60°C (140°F) or higher.
• Turn the air conditioning on (max cool).

• Check the DTC judgment result.

  Powertrain > Engine > Utility 

  Tester Display
  All Readiness

• Input the DTC: P16B8-71.

  Result

  Result	Proceed to
  NORMAL (DTCs are not output)	A
  ABNORMAL (DTC P16B8-71 is output)	B

Post-procedure1

• None.

Result: 

A 

REPLACE ENGINE COOLANT 

Refer to REPLACEMENT [10/2022 - ]

HINT: 

Even when no DTC is output, replace the coolant because foreign matter trapped in the coolant may cause temporary locking.

Result: 

B 

See step  14

HINT: 

Refer to REMOVAL [10/2022 - ]

Result

Result: 

NEXT 

REPLACE ENGINE COOLANT. Refer to  REPLACEMENT [10/2022 - ]